Torsional isolation of a convertless automatic transmission through slip control of friction clutch

A system for controlling operation of a hydraulically-actuated input clutch in an automotive vehicle driveline, the clutch having a variable torque capacity, slip and clutch pressure, the system comprising:

• an internal combustion engine transmitting input torque to the clutch and having a throttle for controlling torque produced by the engine;
• a displaceable accelerator pedal for controlling the engine throttle;
• a displaceable accelerator pedal;
• a transmission for producing multiple gear ratios between the clutch and an output;
• a controller including a closed-loop control and an open-loop control, the controller determining the current magnitude of input torque transmitted to the clutch by the engine;
• monitoring slip speed at the input clutch;
• determining a magnitude of clutch pressure that would produce a torque capacity of the input clutch equal to the current magnitude of input torque;
• monitoring the position of the accelerator pedal to determine whether a transient condition occurs;
• if no transient condition occurs, using the closed-loop control to pressurize the clutch at a magnitude of pressure that produces a predetermined slip of the input clutch at the current magnitude of input torque;
• and if a transient condition occurs, using the open-loop control to reduce said determined magnitude of input clutch pressure by a predetermined magnitude such that slip occurs at the input clutch.